The present invention relates to a regenerative control device of a vehicle using an engine and a motor as driving sources.
In the related art, of hybrid vehicles each mounted with an engine and a traveling motor as driving sources of the vehicle, some hybrid vehicles have been sold in the following configuration. That is, a power generation function is added to the traveling motor while another motor generator than the traveling motor is linked with the engine so that the driving force of the engine can be connected to and disconnected from a power transmission path. That is, generation of a driving force and generation of electric power can be performed in each of the engine and the traveling motor. Such a hybrid vehicle in which a series system and a parallel system are combined can support various vehicle driving modes as compared with an existing driving system such as a simple series system or a simple parallel system. In the series/parallel combined hybrid vehicle, the engine and the traveling motor can be used separately or together in accordance with the traveling state of the vehicle.
The diversity of vehicle driving modes contributes not only to the power performance of the vehicle but also to improvement of energy efficiency in traveling. For example, when regenerative power generation is carried out in the traveling motor during travel, using the driving force of the engine, it is possible to charge a traveling battery or assist a braking force. Even during travel using the driving force of the traveling motor, the traveling battery can be charged with regenerative electric power generated at the time of deceleration, and a braking force can be given to wheels as if an engine brake were operated. Further, when the engine is operated at a rotation speed high in operation efficiency and the motor generator is driven by the engine, the traveling battery can be charged efficiently.
On the other hand, in the hybrid vehicle configured thus, the frequency with which the traveling battery is charged during travel is increased. It is therefore concerned that the battery may be overcharged. Particularly the recovery amount of regenerative electric power generated in the traveling motor affects the magnitude of a braking force in the vehicle. It is therefore desired that the vehicle can travel while recovering the regenerative electric power of the traveling motor in some method even when the traveling battery is almost fully charged.
To this end, there has been proposed a technique in which, of the regenerative electric power of the traveling motor, surplus electric power that is not used for charging the battery is consumed by an air conditioning system. For example, it can be considered that the surplus electric power is assigned for power consumption in a compressor, an air blower, etc. of the air conditioning system so as to improve the cooling capacity or the heating capacity. When such a method is used, it is possible to secure a braking force without overheating the battery, and it is also possible to intend to use electric power effectively (see JP-A-2009-196404).
In addition, there has been proposed a technique in which a motor generator linked with an engine is driven as an electric motor to forcibly rotate the engine that has been stopped. That is, the engine that has been separated from a power transmission path of a vehicle e is used as a rotational load of the motor generator so that electric power can be consumed by the motor generator. Due to such a control, it is possible to perform regenerative braking while regulating charging a traveling battery, so that drive feeling can be improved (see JP-A-2012-6525).
However, regenerative electric power of a vehicle increases and decreases in accordance with the traveling state of the vehicle. The regenerative electric power is not always generated periodically or regularly. As a result, when the regenerative electric power is consumed by an air conditioning system, fluctuation in air conditioning capacity may increase to make the air conditioning performance unstable. In addition, of the air conditioning system mounted on the vehicle, a heating device for heating the inside of a cabin often has a mechanism for generating hot air using heat generated. In an engine. However, heat is not generated when the engine is stopping or when the engine is being forcibly driven to rotate. It is therefore impossible to secure satisfactory heating performance even when the air conditioning system is operated.
Thus, in a related-art hybrid vehicle, there is a problem that it is difficult to make the regenerative braking performance based on recovery of regenerative electric power and the heating performance compatible.